This invention relates to adaptive video synchronization and more particularly to a method and apparatus for adaptively deriving from an unknown analog video input the requisite synchronization signals to allow a digital device to utilize the video input.
Technological advances in video displays have brought increasingly high resolutions and led to an increasing proliferation of video formats. Most recently, attention has been focused on developing a new standard for high definition television (HDTV). Normally, each video format requires its own separate video adapter to render the video signal usable by a digital device. Adaptive video synchronizers are known that are capable of performing synchronization with respect to various formats within a limited range. Although such devices are a useful improvement over the one-format one-adapter situation, they are still unable to handle much of the broad array of video formats presently in use, without regard to the rapid development of new formats.
The numerous video formats presently in use vary widely in terms of their line rate, the number of lines per field, their pixel rates, and the use or non-use of serration (auxiliary timing pulses occurring during vertical synch). The unexpected presence or absence of serrations alone is often enough to confuse a non-adaptive synchronizer, and when coupled with additional variations as previously mentioned presents a bewildering array of possibilities beyond the capability of any of the presently-know video synchronizers.
In digital image processing, since considerable effort and expense is devoted to creating sophisticated hardware and software tools for extracting useful information from a video image, it is desirable to provide the greatest possible compatibility between the image processor and the various video sources that may be used.
The adaptive video synchronization method and apparatus of the present invention may be used to interface a variety of analog video sources including video cameras, video cassette recorders, infrared sensors and video discs to a digital system for military or commercial use. Possible applications of the present invention include digital trackers, automatic target recognizers and symbology or graphics boards.
More broadly, the present invention will find wide application in television with its trends toward digital television, the interfacing/integrating of televisions and computers, and especially the looming arrival of high-definition television (HDTV). The adaptive video synchronization method and apparatus can be used with NTSC, European, or Japanese video types.